deactivating thumbs? (1 post)

Hi, most of you guys probably think the thumbnail function is pretty handy.

Well, in my case, I don't want it, it only takes away (granted, little) space and it doesn't even work on transparencies and often badly decreases the pic's quality. Not to mention, they are just to small in the few cases I do need 'em, so I have to create one myself, anyways (that also helps with keeping transparencies and quality).
So, how can I turn it off?